uBlock/src/js/scriptlets/dom-inspector.js

/*******************************************************************************

    uBlock Origin - a browser extension to block requests.
    Copyright (C) 2015 Raymond Hill

    This program is free software: you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program.  If not, see {http://www.gnu.org/licenses/}.

    Home: https://github.com/gorhill/uBlock
*/

/* global vAPI, HTMLDocument */

/******************************************************************************/
/******************************************************************************/

(function() {

'use strict';

/******************************************************************************/

// https://github.com/gorhill/uBlock/issues/464
if ( document instanceof HTMLDocument === false ) {
    return;
}

// This can happen
if ( typeof vAPI !== 'object' ) {
    return;
}

/******************************************************************************/

if ( document.querySelector('iframe.dom-inspector.' + vAPI.sessionId) !== null ) {
    return;
}

/******************************************************************************/
/******************************************************************************/

// Modified to avoid installing as a global shim -- so the scriptlet can be
// flushed from memory once no longer in use.

/*! http://mths.be/cssescape v0.2.1 by @mathias | MIT license */
var cssEscape = (function(root) {

    var css = root.CSS || {};
    if ( css.escape ) {
        return css.escape;
    }

    var InvalidCharacterError = function(message) {
        this.message = message;
    };
    InvalidCharacterError.prototype = new Error();
    InvalidCharacterError.prototype.name = 'InvalidCharacterError';

    // http://dev.w3.org/csswg/cssom/#serialize-an-identifier
    return function(value) {
        var string = String(value);
        var length = string.length;
        var index = -1;
        var codeUnit;
        var result = '';
        var firstCodeUnit = string.charCodeAt(0);
        while (++index < length) {
            codeUnit = string.charCodeAt(index);
            // Note: there’s no need to special-case astral symbols, surrogate
            // pairs, or lone surrogates.

            // If the character is NULL (U+0000), then throw an
            // `InvalidCharacterError` exception and terminate these steps.
            if (codeUnit === 0x0000) {
                throw new InvalidCharacterError(
                    'Invalid character: the input contains U+0000.'
                );
            }

            if (
                // If the character is in the range [\1-\1F] (U+0001 to U+001F) or is
                // U+007F, […]
                (codeUnit >= 0x0001 && codeUnit <= 0x001F) || codeUnit == 0x007F ||
                // If the character is the first character and is in the range [0-9]
                // (U+0030 to U+0039), […]
                (index === 0 && codeUnit >= 0x0030 && codeUnit <= 0x0039) ||
                // If the character is the second character and is in the range [0-9]
                // (U+0030 to U+0039) and the first character is a `-` (U+002D), […]
                (
                    index == 1 &&
                    codeUnit >= 0x0030 && codeUnit <= 0x0039 &&
                    firstCodeUnit == 0x002D
                )
            ) {
                // http://dev.w3.org/csswg/cssom/#escape-a-character-as-code-point
                result += '\\' + codeUnit.toString(16) + ' ';
                continue;
            }

            // If the character is not handled by one of the above rules and is
            // greater than or equal to U+0080, is `-` (U+002D) or `_` (U+005F), or
            // is in one of the ranges [0-9] (U+0030 to U+0039), [A-Z] (U+0041 to
            // U+005A), or [a-z] (U+0061 to U+007A), […]
            if (
                codeUnit >= 0x0080 ||
                codeUnit == 0x002D ||
                codeUnit == 0x005F ||
                codeUnit >= 0x0030 && codeUnit <= 0x0039 ||
                codeUnit >= 0x0041 && codeUnit <= 0x005A ||
                codeUnit >= 0x0061 && codeUnit <= 0x007A
            ) {
                // the character itself
                result += string.charAt(index);
                continue;
            }

            // Otherwise, the escaped character.
            // http://dev.w3.org/csswg/cssom/#escape-a-character
            result += '\\' + string.charAt(index);

        }
        return result;
    };

}(self));

/******************************************************************************/
/******************************************************************************/

var localMessager = vAPI.messaging.channel('dom-inspector.js');

// Highlighter-related
var svgOcean = null;
var svgIslands = null;
var svgRoot = null;
var pickerRoot = null;
var currentSelector = '';

var toggledNodes = new Map();

/******************************************************************************/

// Some kind of fingerprint for the DOM, without incurring too much overhead.

var domFingerprint = function() {
    return vAPI.sessionId;
};

/******************************************************************************/

var domLayout = (function() {
    var skipTagNames = {
        'br': true,
        'link': true,
        'meta': true,
        'script': true,
        'style': true
    };

    var resourceAttrNames = {
        'a': 'href',
        'iframe': 'src',
        'img': 'src',
        'object': 'data'
    };

    var idGenerator = 0;
    var nodeToIdMap = new WeakMap(); // No need to iterate

    // This will be used to uniquely identify nodes across process.

    var newNodeId = function(node) {
        var nid = 'n' + (idGenerator++).toString(36);
        nodeToIdMap.set(node, nid);
        return nid;
    };

    // Collect all nodes which are directly affected by cosmetic filters: these
    // will be reported in the layout data.
    // TODO: take into account cosmetic filters added after the map is build.

    var nodeToCosmeticFilterMap = (function() {
        var out = new WeakMap();
        var styleTags = vAPI.styles || [];
        var i = styleTags.length;
        var selectors, styleText, j, selector, nodes, k;
        while ( i-- ) {
            styleText = styleTags[i].textContent;
            selectors = styleText.slice(0, styleText.lastIndexOf('\n')).split(/,\n/);
            j = selectors.length;
            while ( j-- ) {
                selector = selectors[j];
                nodes = document.querySelectorAll(selector);
                k = nodes.length;
                while ( k-- ) {
                    out.set(nodes[k], selector);
                }
            }
        }
        return out;
    })();

    var matchesSelector = (function() {
        if ( typeof Element.prototype.matches === 'function' ) {
            return 'matches';
        }
        if ( typeof Element.prototype.mozMatchesSelector === 'function' ) {
            return 'mozMatchesSelector';
        }
        if ( typeof Element.prototype.webkitMatchesSelector === 'function' ) {
            return 'webkitMatchesSelector';
        }
        return '';
    })();

    var hasManyMatches = function(node, selector) {
        var fnName = matchesSelector;
        if ( fnName === '' ) {
            return true;
        }
        var child = node.firstElementChild;
        var match = false;
        while ( child !== null ) {
            if ( child[fnName](selector) ) {
                if ( match ) {
                    return true;
                }
                match = true;
            }
            child = child.nextElementSibling;
        }
        return false;
    };

    var selectorFromNode = function(node) {
        var str, attr, pos, sw, i;
        var tag = node.localName;
        var selector = cssEscape(tag);
        // Id
        if ( typeof node.id === 'string' ) {
            str = node.id.trim();
            if ( str !== '' ) {
                selector += '#' + cssEscape(str);
            }
        }
        // Class
        var cl = node.classList;
        if ( cl ) {
            for ( i = 0; i < cl.length; i++ ) {
                selector += '.' + cssEscape(cl[i]);
            }
        }
        // Tag-specific attributes
        if ( resourceAttrNames.hasOwnProperty(tag) ) {
            attr = resourceAttrNames[tag];
            str = node.getAttribute(attr) || '';
            str = str.trim();
            pos = str.indexOf('#');
            if ( pos !== -1 ) {
                str = str.slice(0, pos);
                sw = '^';
            } else {
                sw = '';
            }
            if ( str !== '' ) {
                selector += '[' + attr + sw + '="' + cssEscape(str) + '"]';
            }
        }
        // The resulting selector must cause only one element to be selected. If
        // it's not the case, further narrow using `nth-of-type` pseudo-class.
        if ( hasManyMatches(node.parentElement, selector) ) {
            i = 1;
            while ( node.previousElementSibling ) {
                node = node.previousElementSibling;
                if ( node.localName === tag ) {
                    i += 1;
                }
            }
            selector += ':nth-of-type(' + i + ')';
        }
        return selector;
    };

    var DomRoot = function() {
        this.nid = newNodeId(document.body);
        this.lvl = 0;
        this.sel = 'body';
        this.cnt = 0;
        this.filter = nodeToCosmeticFilterMap.get(document.body);
    };

    var DomNode = function(node, level) {
        this.nid = newNodeId(node);
        this.lvl = level;
        this.sel = selectorFromNode(node);
        this.cnt = 0;
        this.filter = nodeToCosmeticFilterMap.get(node);
    };

    var domNodeFactory = function(level, node) {
        var localName = node.localName;
        if ( skipTagNames.hasOwnProperty(localName) ) {
            return null;
        }
        // skip uBlock's own nodes
        if ( node.classList.contains(vAPI.sessionId) ) {
            return null;
        }
        if ( level === 0 && localName === 'body' ) {
            return new DomRoot();
        }
        return new DomNode(node, level);
    };

    // Collect layout data.

    var getLayoutData = function() {
        var layout = [];
        var stack = [];
        var node = document.body;
        var domNode;
        var lvl = 0;

        for (;;) {
            domNode = domNodeFactory(lvl, node);
            if ( domNode !== null ) {
                layout.push(domNode);
            }
            // children
            if ( node.firstElementChild !== null ) {
                stack.push(node);
                lvl += 1;
                node = node.firstElementChild;
                continue;
            }
            // sibling
            if ( node.nextElementSibling === null ) {
                do {
                    node = stack.pop();
                    if ( !node ) { break; }
                    lvl -= 1;
                } while ( node.nextElementSibling === null );
                if ( !node ) { break; }
            }
            node = node.nextElementSibling;
        }

        return layout;
    };

    // Descendant count for each node.

    var patchLayoutData = function(layout) {
        var stack = [], ptr;
        var lvl = 0;
        var domNode, cnt;
        var i = layout.length;

        while ( i-- ) {
            domNode = layout[i];
            if ( domNode.lvl === lvl ) {
                stack[ptr] += 1;
                continue;
            }
            if ( domNode.lvl > lvl ) {
                while ( lvl < domNode.lvl ) {
                    stack.push(0);
                    lvl += 1;
                }
                ptr = lvl - 1;
                stack[ptr] += 1;
                continue;
            }
            // domNode.lvl < lvl
            cnt = stack.pop();
            domNode.cnt = cnt;
            lvl -= 1;
            ptr = lvl - 1;
            stack[ptr] += cnt + 1;
        }
        return layout;
    };

    // Track and report mutations to the DOM

    var journalEntries = [];
    var journalNodes = Object.create(null);

    var mutationObserver = null;
    var mutationTimer = null;
    var addedNodelists = [];
    var removedNodelist = [];

    var previousElementSiblingId = function(node) {
        var sibling = node;
        for (;;) {
            sibling = sibling.previousElementSibling;
            if ( sibling === null ) {
                return null;
            }
            if ( skipTagNames.hasOwnProperty(sibling.localName) ) {
                continue;
            }
            return nodeToIdMap.get(sibling);
        }
    };

    var journalFromBranch = function(root, added) {
        var domNode;
        var node = root.firstElementChild;
        while ( node !== null ) {
            domNode = domNodeFactory(undefined, node);
            if ( domNode !== null ) {
                journalNodes[domNode.nid] = domNode;
                added.push(node);
            }
            // down
            if ( node.firstElementChild !== null ) {
                node = node.firstElementChild;
                continue;
            }
            // right
            if ( node.nextElementSibling !== null ) {
                node = node.nextElementSibling;
                continue;
            }
            // up then right
            for (;;) {
                if ( node.parentElement === root ) {
                    return;
                }
                node = node.parentElement;
                if ( node.nextElementSibling !== null ) {
                    node = node.nextElementSibling;
                    break;
                }
            }
        }
    };

    var journalFromMutations = function() {
        mutationTimer = null;
        if ( mutationObserver === null ) {
            addedNodelists = [];
            removedNodelist = [];
            return;
        }

        var i, m, nodelist, j, n, node, domNode, nid;

        // This is used to temporarily hold all added nodes, before resolving
        // their node id and relative position.
        var added = [];

        for ( i = 0, m = addedNodelists.length; i < m; i++ ) {
            nodelist = addedNodelists[i];
            for ( j = 0, n = nodelist.length; j < n; j++ ) {
                node = nodelist[j];
                if ( node.nodeType !== 1 ) {
                    continue;
                }
                // I don't think this can ever happen
                if ( node.parentElement === null ) {
                    continue;
                }
                domNode = domNodeFactory(undefined, node);
                if ( domNode !== null ) {
                    journalNodes[domNode.nid] = domNode;
                    added.push(node);
                }
                journalFromBranch(node, added);
            }
        }
        addedNodelists = [];
        for ( i = 0, m = removedNodelist.length; i < m; i++ ) {
            nodelist = removedNodelist[i];
            for ( j = 0, n = nodelist.length; j < n; j++ ) {
                node = nodelist[j];
                if ( node.nodeType !== 1 ) {
                    continue;
                }
                nid = nodeToIdMap.get(node);
                if ( nid === undefined ) {
                    continue;
                }
                journalEntries.push({
                    what: -1,
                    nid: nid
                });
            }
        }
        removedNodelist = [];
        for ( i = 0, n = added.length; i < n; i++ ) {
            node = added[i];
            journalEntries.push({
                what: 1,
                nid: nodeToIdMap.get(node),
                u: nodeToIdMap.get(node.parentElement),
                l: previousElementSiblingId(node)
            });
        }
    };

    var onMutationObserved = function(mutationRecords) {
        var record;
        for ( var i = 0, n = mutationRecords.length; i < n; i++ ) {
            record = mutationRecords[i];
            if ( record.addedNodes.length !== 0 ) {
                addedNodelists.push(record.addedNodes);
            }
            if ( record.removedNodes.length !== 0 ) {
                removedNodelist.push(record.removedNodes);
            }
        }
        if ( mutationTimer === null ) {
            mutationTimer = vAPI.setTimeout(journalFromMutations, 1000);
        }
    };

    // API

    var getLayout = function(fingerprint) {
        if ( fingerprint !== domFingerprint() && mutationObserver !== null ) {
            if ( mutationTimer !== null ) {
                clearTimeout(mutationTimer);
                mutationTimer = null;
            }
            mutationObserver.disconnect();
            mutationObserver = null;
            journalEntries = [];
            journalNodes = Object.create(null);
        }

        var response = {
            what: 'domLayout',
            fingerprint: domFingerprint()
        };

        // No mutation observer means we need to send full layout
        if ( mutationObserver === null ) {
            mutationObserver = new MutationObserver(onMutationObserved);
            mutationObserver.observe(document.body, {
                childList: true,
                subtree: true
            });
            response.status = 'full';
            response.layout = patchLayoutData(getLayoutData());
            return response;
        }

        // Incremental layout
        if ( journalEntries.length !== 0 ) {
            response.status = 'incremental';
            response.journal = journalEntries;
            response.nodes = journalNodes;
            journalEntries = [];
            journalNodes = Object.create(null);
            return response;
        }

        response.status = 'nochange';
        return response;
    };

    var shutdown = function() {
        if ( mutationTimer !== null ) {
            clearTimeout(mutationTimer);
            mutationTimer = null;
        }
        if ( mutationObserver !== null ) {
            mutationObserver.disconnect();
            mutationObserver = null;
        }
        journalEntries = [];
        journalNodes = Object.create(null);
    };

    return {
        get: getLayout,
        shutdown: shutdown
    };
})();

/******************************************************************************/

var highlightElements = function(elems, scrollTo) {
    var wv = pickerRoot.contentWindow.innerWidth;
    var hv = pickerRoot.contentWindow.innerHeight;
    var ocean = ['M0 0h' + wv + 'v' + hv + 'h-' + wv, 'z'];
    var islands = [];
    var elem, rect, poly;
    var xl, xr, yt, yb, w, h, ws;
    var xlu = Number.MAX_VALUE, xru = 0, ytu = Number.MAX_VALUE, ybu = 0;

    for ( var i = 0; i < elems.length; i++ ) {
        elem = elems[i];
        if ( elem === pickerRoot ) {
            continue;
        }
        if ( typeof elem.getBoundingClientRect !== 'function' ) {
            continue;
        }

        rect = elem.getBoundingClientRect();
        xl = rect.left;
        xr = rect.right;
        w = rect.width;
        yt = rect.top;
        yb = rect.bottom;
        h = rect.height;

        ws = w.toFixed(1);
        poly = 'M' + xl.toFixed(1) + ' ' + yt.toFixed(1) +
               'h' + ws +
               'v' + h.toFixed(1) +
               'h-' + ws +
               'z';
        ocean.push(poly);
        islands.push(poly);

        if ( !scrollTo ) {
            continue;
        }

        if ( xl < xlu ) { xlu = xl; }
        if ( xr > xru ) { xru = xr; }
        if ( yt < ytu ) { ytu = yt; }
        if ( yb > ybu ) { ybu = yb; }
    }
    svgOcean.setAttribute('d', ocean.join(''));
    svgIslands.setAttribute('d', islands.join('') || 'M0 0');

    if ( !scrollTo ) {
        return;
    }

    // Highlighted area completely within viewport
    if ( xlu >= 0 && xru <= wv && ytu >= 0 && ybu <= hv ) {
        return;
    }

    var dx = 0, dy = 0;

    if ( xru > wv ) {
        dx = xru - wv;
        xlu -= dx;
    }
    if ( xlu <  0 ) {
        dx += xlu;
    }
    if ( ybu > hv ) {
        dy = ybu - hv;
        ytu -= dy;
    }
    if ( ytu <  0 ) {
        dy += ytu;
    }

    if ( dx !== 0 || dy !== 0 ) {
        window.scrollBy(dx, dy);
    }
};

/******************************************************************************/

var elementsFromSelector = function(filter) {
    var out = [];
    try {
        out = document.querySelectorAll(filter);
    } catch (ex) {
    }
    return out;
};

/******************************************************************************/

var highlight = function(scrollTo) {
    var elements = elementsFromSelector(currentSelector);
    highlightElements(elements, scrollTo);
};

/******************************************************************************/

var onScrolled = function() {
    highlight();
};

/******************************************************************************/

// original, target = what to do
//      any,    any = restore saved display property
//      any, hidden = set display to `none`, remember original state
//   hidden,    any = remove display property, don't remember original state
//   hidden, hidden = set display to `none`

var toggleNodes = function(selector, originalState, targetState) {
    var nodes = document.querySelectorAll(selector);
    var i = nodes.length;
    if ( i === 0 ) {
        return;
    }
    var node, value;
    while ( i-- ) {
        node = nodes[i];
        if ( originalState ) {                              // any, ?
            if ( targetState ) {                            // any, any
                value = toggledNodes.get(node);
                if ( value === undefined ) {
                    continue;
                }
                if ( value !== null ) {
                    node.style.removeProperty('display');
                } else {
                    node.style.setProperty('display', value);
                }
                toggledNodes.delete(node);
            } else {                                        // any, hidden
                toggledNodes.set(node, node.style.getPropertyValue('display') || null);
                node.style.setProperty('display', 'none');
            }
        } else {                                            // hidden, ?
            if ( targetState ) {                            // hidden, any
                node.style.setProperty('display', 'initial', 'important');
            } else {                                        // hidden, hidden
                node.style.setProperty('display', 'none', 'important');
            }
        }
    }
};

/******************************************************************************/

var resetToggledNodes = function() {
    var value;
    // Chromium does not support destructuring as of v43.
    for ( var node of toggledNodes.keys() ) {
        value = toggledNodes.get(node);
        if ( value !== null ) {
            node.style.removeProperty('display');
        } else {
            node.style.setProperty('display', value);
        }
    }
    toggledNodes.clear();
};

/******************************************************************************/

var shutdown = function() {
    resetToggledNodes();
    domLayout.shutdown();
    localMessager.removeListener(onMessage);
    localMessager.close();
    localMessager = null;
    window.removeEventListener('scroll', onScrolled, true);
    document.documentElement.removeChild(pickerRoot);
    pickerRoot = svgRoot = svgOcean = svgIslands = null;
    currentSelector = '';
};

/******************************************************************************/

var onMessage = function(request) {
    var msg = request.what === 'postMessageTo' ? request.msg : request;
    var response;

    switch ( msg.what ) {
    case 'domLayout':
        response = domLayout.get(msg.fingerprint);
        break;

    case 'highlight':
        currentSelector = msg.selector;
        highlight(msg.scrollTo);
        break;

    case 'toggleNodes':
        toggleNodes(msg.selector, msg.original, msg.target);
        currentSelector = msg.selector;
        highlight(true);
        break;

    case 'shutdown':
        shutdown();
        break;

    default:
        break;
    }

    if ( response !== undefined && request.what === 'postMessageTo' ) {
        localMessager.send({
            what: 'postMessageTo',
            senderTabId: null,
            senderChannel: 'dom-inspector.js',
            receiverTabId: request.senderTabId,
            receiverChannel: request.senderChannel,
            msg: response
        });
    }
};

/******************************************************************************/

// Install DOM inspector widget

pickerRoot = document.createElement('iframe');
pickerRoot.classList.add(vAPI.sessionId);
pickerRoot.classList.add('dom-inspector');
pickerRoot.style.cssText = [
    'background: transparent',
    'border: 0',
    'border-radius: 0',
    'box-shadow: none',
    'display: block',
    'height: 100%',
    'left: 0',
    'margin: 0',
    'opacity: 1',
    'position: fixed',
    'outline: 0',
    'padding: 0',
    'top: 0',
    'visibility: visible',
    'width: 100%',
    'z-index: 2147483647',
    ''
].join(' !important;\n');

pickerRoot.onload = function() {
    pickerRoot.onload = null;
    var pickerDoc = this.contentDocument;

    var style = pickerDoc.createElement('style');
    style.textContent = [
        'body {',
            'background-color: transparent;',
            'cursor: crosshair;',
        '}',
        'svg {',
            'height: 100%;',
            'left: 0;',
            'position: fixed;',
            'top: 0;',
            'width: 100%;',
        '}',
        'svg > path:first-child {',
            'fill: rgba(0,0,0,0.75);',
            'fill-rule: evenodd;',
        '}',
        'svg > path + path {',
            'fill: rgba(0,0,255,0.1);',
            'stroke: #FFF;',
            'stroke-width: 0.5px;',
        '}',
        ''
    ].join('\n');
    pickerDoc.body.appendChild(style);

    svgRoot = pickerDoc.createElementNS('http://www.w3.org/2000/svg', 'svg');
    svgOcean = pickerDoc.createElementNS('http://www.w3.org/2000/svg', 'path');
    svgRoot.appendChild(svgOcean);
    svgIslands = pickerDoc.createElementNS('http://www.w3.org/2000/svg', 'path');
    svgRoot.appendChild(svgIslands);
    pickerDoc.body.appendChild(svgRoot);

    window.addEventListener('scroll', onScrolled, true);

    highlight();

    localMessager.addListener(onMessage);
};

document.documentElement.appendChild(pickerRoot);

/******************************************************************************/

})();

/******************************************************************************/